1. Technical Field
The present inventive concept relates to semiconductor memory devices and, more particularly, to a semiconductor memory device including a flash memory and a random access memory (RAM) and an operating method thereof.
2. Discussion of Related Art
Generally, semiconductor memory devices are categorized as volatile memory devices or non-volatile memory devices. The volatile memory devices are classified into dynamic random access memory (DRAM) devices, which use a capacitor and a transistor per bit, and static random access memory (SRAM) devices, which rely on several transistors per bit, for example. The volatile memory devices generally operate at a higher speed than the non-volatile memory devices but require power to maintain their stored data.
The non-volatile memory devices include mask read-only memory (MROM) devices, programmable read-only memory (PROM) devices, erasable programmable read-only memory (EPROM) devices, and electrically erasable programmable read-only memory (EEPROM) devices, for example. The non-volatile memory devices can retain their stored data when not powered but have lower read/write speeds than the volatile memory devices.
However, data stored in MROM devices and PROM devices is not rewritable, and data stored in EPROM devices can be rewritten but an EPROM usually must be removed from the device for erasing and programming. On the other hand, EEPROM devices can be erased and reprogrammed repeatedly through the application of an electrical voltage generated externally or internally, and thus, are increasingly used in system programming that is continuously updated or as auxiliary memory devices.
Flash memory devices, which are a specific type of EEPROM device, are increasingly used as mass storage devices because their integration density is higher than traditional EEPROM devices. Among the flash memory devices, a NAND flash memory device has a higher integration density than a NOR flash memory device. As flash memory devices, such as a high-density NAND flash memory device, continue to be adopted in a variety of devices, there is a need for a flash memory device with improved operability.